Light guide and lighting assembly with array of rotated micro-optical elements

ABSTRACT

A light guide includes opposed major surfaces and a light input edge extending therebetween. An array of micro-optical elements of well-defined shape at at least one of the opposed major surfaces corresponds to the light input edge. Each of the micro-optical elements in the array includes a longitudinal axis arranged within the range of angles relative to the light input edge. A path linearly extending along the light guide from the light input edge intersects at least a portion of the micro-optical elements in the array, at least one of the micro-optical elements along the path arranged with its longitudinal axis at a positive angle relative to the light input edge, and at least another one of the micro-optical elements along the path arranged with its longitudinal axis at a negative angle relative to the light input edge.

RELATED APPLICATION DATA

This application claims the benefit of U.S. Provisional PatentApplication No. 61/985,052, filed Apr. 28, 2014; and claims the benefitof U.S. Provisional Patent Application No. 62/032,057, filed Aug. 1,2014; the disclosures of which are incorporated herein by reference intheir entireties.

BACKGROUND

Light emitting diodes (LEDs) show promise as an energy efficient lightsource for lighting assemblies. For some LED-based lighting assemblies,the light emitted from the light source is input to a light guide andlight extracting elements specularly extract the light from the lightguide in a defined direction. But these light extracting elements alsoprovide an optically-specular path through which the light source isvisible to a viewer. Reducing the visibility of the light source whilemaintaining the directional, specular light output is desirable in manyapplications for maximum application efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of an exemplary lightingassembly.

FIG. 2 is a schematic view of part of an exemplary embodiment of thelighting assembly of FIG. 1.

FIG. 3 is an output distribution profile of an exemplary lightingassembly.

FIG. 4 is a schematic view of part of an exemplary embodiment of thelighting assembly of FIG. 1.

FIGS. 5 and 6 are scanning electron microscope (“SEM”) images ofexemplary micro-optical elements.

FIGS. 7-10 are output distribution profiles of exemplary lightingassemblies.

FIGS. 11-14 are schematic views showing exemplary lighting assemblies.

DESCRIPTION

Embodiments will now be described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. The figures are not necessarily to scale. Features that aredescribed and/or illustrated with respect to one embodiment may be usedin the same way or in a similar way in one or more other embodimentsand/or in combination with or instead of the features of the otherembodiments. In this disclosure, angles of incidence, reflection, andrefraction and output angles are measured relative to the normal to thesurface.

In accordance with one aspect of the present disclosure, a light guideincludes opposed major surfaces between which light propagates by totalinternal reflection. A light input edge extends between the majorsurfaces in a thickness direction through which light is input into thelight guide. An array of micro-optical elements of well-defined shape isat at least one of the opposed major surfaces, the array ofmicro-optical elements corresponding to the light input edge, each ofthe micro-optical elements in the array having a longitudinal axisarranged within the range of +45° to −45° relative to the light inputedge. A path linearly extending along the light guide from the lightinput edge intersects at least a portion of the micro-optical elementsin the array, at least one of the micro-optical elements along the patharranged with the longitudinal axis thereof at a positive angle relativeto the light input edge, and at least another one of the micro-opticalelements along the path arranged with the longitudinal axis thereof at anegative angle relative to the light input edge.

In accordance with another aspect of the present disclosure, a lightingassembly includes a light guide and a light source. The light guide isconfigured to propagate light by total internal reflection, the lightguide including opposed major surfaces and a light input edge extendingbetween the major surfaces in a thickness direction through which lightis input into the light guide. The light source is located adjacent thelight input edge to edge light the light guide. An array ofmicro-optical elements of well-defined shape is at at least one of theopposed major surfaces, the array of micro-optical elementscorresponding to the light source, each of the micro-optical elements inthe array comprising a longitudinal axis arranged within the range of+45° to −45° relative to the light input edge. A path linearly extendingalong the light guide from the light input edge intersects at least aportion of the micro-optical elements in the array, at least one of themicro-optical elements along the path arranged with the longitudinalaxis thereof at a positive angle relative to the light input edge, andat least another one of the micro-optical elements along the patharranged with the longitudinal axis thereof at a negative angle relativeto the light input edge.

In accordance with another aspect of the present disclosure, a lightingassembly includes a light guide and a light source. The light guide isconfigured to propagate light by total internal reflection, the lightguide comprising opposed major surfaces and a light input edge extendingbetween the major surfaces in a thickness direction through which lightis input into the light guide, a tangent of at least part of the lightinput edge extending in a direction orthogonal to the thicknessdirection. The light source is located adjacent the light input edge toedge light the light guide. An array of micro-optical elements ofwell-defined shape is at at least one of the opposed major surfaces, thearray of micro-optical elements corresponding to the light source, eachof the micro-optical elements in the array comprising a longitudinalaxis arranged within the range of +45° to −45° relative to the tangentof the light input edge. A path linearly extending along the light guidefrom the light input edge intersects at least a portion of themicro-optical elements of the array, at least one of the micro-opticalelements along the path arranged with the longitudinal axis thereof at apositive angle relative to the tangent of the light input edge, and atleast another one of the micro-optical elements along the path arrangedwith the longitudinal axis thereof at a negative angle relative to thetangent of the light input edge.

With initial reference to FIG. 1, an exemplary embodiment of a lightingassembly is shown at 100. The lighting assembly 100 includes a lightguide 102. The light guide 102 is a solid article of manufacture madefrom, for example, polycarbonate, poly(methyl-methacrylate) (PMMA),glass, or other appropriate material. The light guide 102 may also be amulti-layer light guide having two or more layers that may differ inrefractive index. The light guide 102 includes a first major surface 106and a second major surface 108 opposite the first major surface 106. Thelight guide 102 is configured to propagate light by total internalreflection between the first major surface 106 and the second majorsurface 108. The length and width dimensions of each of the majorsurfaces 106, 108 are greater, typically ten or more times greater, thanthe thickness of the light guide 102. The thickness is the dimension ofthe light guide 102 in a direction orthogonal to the major surfaces 106,108. The thickness of the light guide 102 may be, for example, about 0.1millimeters (mm) to about 10 mm.

At least one edge surface extends between the major surfaces 106, 108 ofthe light guide in the thickness direction. The total number of edgesurfaces depends on the configuration of the light guide. In the casewhere the light guide is rectangular, the light guide has four edgesurfaces 110, 112, 114, 116. Other light guide shapes result in acorresponding number of side edges. Although not shown, in someembodiments, the light guide 102 may additionally include one or moreedge surfaces defined by the perimeter of an orifice extending throughthe light guide in the thickness direction. Each edge surface defined bythe perimeter of an orifice extending through the light guide 102 willhereinafter be referred to as an internal edge surface. Depending on theshape of the light guide 102, each edge surface may be straight orcurved, and adjacent edge surfaces may meet at a vertex or join in acurve. Moreover, each edge surface may include one or more straightportions connected to one or more curved portions. The edge surfacethrough which light from the light source 104 is input to the lightguide will now be referred to as a light input edge. In the embodimentshown in FIG. 1, the edge surface 110 is a light input edge. In someembodiments, the light guide 102 includes more than one light inputedge. Furthermore, the one or more light input edges may be straightand/or curved.

In the illustrated embodiment, the major surfaces 106, 108 are planar.In other embodiments, at least a portion of the major surfaces 106, 108of the light guide 102 is curved in one or more directions. In oneexample, the intersection of the light input edge 110 and one of themajor surfaces 106, 108 defines a first axis, and at least a portion ofthe light guide 102 curves about an axis orthogonal to the first axis.In another example, at least a portion of the light guide 102 curvesabout an axis parallel to the first axis. Exemplary shapes of the lightguide include a dome, a hollow cylinder, a hollow cone or pyramid, ahollow frustrated cone or pyramid, a bell shape, an hourglass shape, oranother suitable shape.

The lighting assembly 100 includes a light source 104 positionedadjacent the light input edge 110. The light source 104 is configured toedge light the light guide 102 such that light from the light source 104enters the light input edge 110 and propagates along the light guide 102by total internal reflection at the major surfaces 106, 108.

The light source 104 includes one or more solid-state light emitters118. The solid-state light emitters 118 constituting the light source104 are arranged linearly or in another suitable pattern depending onthe shape of the light input edge 110 of the light guide 102 to whichthe light source 104 supplies light.

Exemplary solid-state light emitters 118 include such devices as LEDs,laser diodes, and organic LEDs (OLEDs). In an embodiment where thesolid-state light emitters 118 are LEDs, the LEDs may be top-fire LEDsor side-fire LEDs, and may be broad spectrum LEDs (e.g., white lightemitters) or LEDs that emit light of a desired color or spectrum (e.g.,red light, green light, blue light, or ultraviolet light), or a mixtureof broad-spectrum LEDs and LEDs that emit narrow-band light of a desiredcolor. In one embodiment, the solid-state light emitters 118 emit lightwith no operably-effective intensity at wavelengths greater than 500nanometers (nm) (i.e., the solid-state light emitters 118 emit light atwavelengths that are predominantly less than 500 nm). In someembodiments, the solid-state light emitters 118 constituting lightsource 104 all generate light having the same nominal spectrum. In otherembodiments, at least some of the solid-state light emitters 118constituting light source 104 generate light that differs in spectrumfrom the light generated by the remaining solid-state light emitters118. For example, two different types of solid-state light emitters 118may be alternately located along the light source 104.

Each solid-state light emitter 118 emits light at a light ray angledistribution relative to an optical axis 119 (FIGS. 2 and 4) of thesolid-state light emitter 118. The optical axis 119 is defined as anaxis extending orthogonally from the center of the light emittingsurface of the solid state light emitter 118. The solid-state lightemitter 118 may be arranged so that the optical axis 119 isperpendicular to the light input edge 110.

The lighting assembly 100 may include one or more additional components.For example, although not specifically shown in detail, in someembodiments of the lighting assembly, the light source 104 includesstructural components to retain the solid-state light emitters 118. Inthe examples shown in FIG. 1, the solid-state light emitters 118 aremounted to a printed circuit board (PCB) 120. The light source 104 mayadditionally include circuitry, power supply, electronics forcontrolling and driving the solid-state light emitters 118, and/or anyother appropriate components.

The lighting assembly 100 may additionally include a housing 122 forretaining the light source 104 and the light guide 102. The housing 122may retain a heat sink or may itself function as a heat sink. In someembodiments, the lighting assembly 100 includes a mounting mechanism(not shown) to mount the lighting assembly to a retaining structure(e.g., a ceiling, a wall, etc.).

The lighting assembly 100 may additionally include a reflector (notshown) adjacent one of the major surfaces 106, 108. The light extractedthrough the major surface adjacent the reflector may be reflected by thereflector, re-enter the light guide 102 at the major surface, and beoutput from the light guide 102 through the other major surface.

The light guide 102 includes light extracting elements embodied asmicro-optical elements 124 in, on, or beneath at least one of the majorsurfaces 106, 108. Micro-optical elements that are in, on, or beneath amajor surface will be referred to as being “at” the major surface. Themicro-optical elements 124 are features of well-defined shape thatpredictably reflect or refract the light propagating in the light guide102. In some embodiments, at least one of the micro-optical elements 124is an indentation in the major surface 106, 108 of well-defined shape.In other embodiments, at least one of the micro-optical elements 124 isa protrusion from the major surface 106, 108 of well-defined shape.

A micro-optical element of well-defined shape is a three-dimensionalfeature recessed into a major surface or protruding from a major surfacehaving distinct surfaces on a scale larger than the surface roughness ofthe major surfaces 106, 108. Micro-optical elements and micro-featuresof well-defined shape exclude features of indistinct shape or surfacetextures, such as printed features of indistinct shape, ink jet printedfeatures of indistinct shape, selectively-deposited features ofindistinct shape, and features of indistinct shape wholly formed bychemical etching or laser etching.

Light guides having micro-optical elements are typically formed by aprocess such as injection molding. The light-extracting elements aretypically defined in a shim or insert used for injection molding lightguides by a process such as diamond machining, laser micromachining,photolithography, or another suitable process. Alternatively, any of theabove-mentioned processes may be used to define the light-extractingelements in a master that is used to make the shim or insert. In otherembodiments, light guides without micro-optical elements are typicallyformed by a process such as injection molding or extruding, and thelight-extracting elements are subsequently formed on one or both of themajor surfaces by a process such as stamping, embossing, or anothersuitable process.

Each micro-optical element 124 functions to disrupt the total internalreflection of the light propagating in the light guide and incidentthereon. In one embodiment, the micro-optical elements 124 reflect lighttoward the opposing major surface so that the light exits the lightguide 102 through the opposing major surface. Alternatively, themicro-optical elements 124 transmit light through the micro-opticalelements 124 and out of the major surface of the light guide 102 havingthe micro-optical elements 124. In another embodiment, both types ofmicro-optical elements 124 are present. In yet another embodiment, themicro-optical elements 124 reflect some of the light and refract theremainder of the light incident thereon. Therefore, the micro-opticalelements 124 are configured to extract light from the light guide 102through one or both of the major surfaces 106, 108.

The micro-optical elements 124 are configured to extract light in adefined intensity profile (e.g., a uniform intensity profile) and with adefined light ray angle distribution from one or both of the majorsurfaces 106, 108. In this disclosure, intensity profile refers to thevariation of intensity with regard to position within a light-emittingregion (such as the major surface or a light output region of the majorsurface). The term light ray angle distribution is used to describe thevariation of the intensity of light with ray angle (typically a solidangle) over a defined range of light ray angles. In an example in whichthe light is emitted from an edge-lit light guide, the light ray anglescan range from −90° to +90° relative to the normal to the major surface.

Micro-optical elements 124 are small relative to the linear dimensionsof the major surfaces 106, 108. The smaller of the length and width of amicro-optical element 124 is less than one-tenth of the longer of thelength and width (or circumference) of the light guide 102 and thelarger of the length and width of the micro-optical element 124 is lessthan one-half of the smaller of the length and width (or circumference)of the light guide 102. The length and width of the micro-opticalelement 124 is measured in a plane parallel to the major surface 106,108 of the light guide 102 for planar light guides or along a surfacecontour for non-planar light guides 102.

The micro-optical elements 124 can be any suitable shape. As an example,the light guide 102 shown in FIG. 1 includes micro-optical elements 124at the major surface 106 configured as v-groove-shaped depressionshaving an arcuate ridge, hereinafter referred to as “football-shaped”micro-optical elements. A football-shaped micro-optical elementresembles the profile of the ball used in American football. Eachfootball-shaped micro-optical element 124 includes a first side surface126 and a second side surface 128 that come together to form a ridge 130having ends that intersect the one of the major surfaces 106, 108 atwhich the micro-optical element 124 is formed. The included angle formedbetween the first side surface 126 and the second side surface 128 maybe any suitable angle. The included angles of the respectivemicro-optical elements 124 may be set for extracting light from thelight guide 102 at a defined intensity profile and/or light ray angledistribution. As an example, the included angles of the respectivefootball-shaped micro-optical elements 124 may range from 40 degrees to165 degrees. In some embodiments, at least one of the first side surface126 and the second side surface 128 is curved. In other embodiments, atleast one of the first side surface 126 and the second side surface 128is planar. In some embodiments, the first side surface 126 and thesecond side surface 128 are symmetric relative to a plane extendingparallel to and intersecting the ridge 130, and extending normal to themajor surface. In other embodiments, the first side surface 126 and thesecond side surface 138 are asymmetric relative to a plane extendingparallel to and intersecting the ridge 130, and extending normal to themajor surface.

Other exemplary embodiments of the light guide 102 may includemicro-optical elements 124 having other suitable shapes. In an example,one or more of the micro-optical elements may be configured as a draggedtruncated cone (not shown) having a pair of opposed oppositely slopingplanar sides and opposed oppositely rounded or curved ends, and a planartop intersecting the oppositely sloping sides and oppositely roundedends. Other exemplary micro-optical elements 124 are described in U.S.Pat. No. 6,752,505, the entire content of which is incorporated byreference, and, for the sake of brevity, are not described in detail inthis disclosure.

At least a portion of the micro-optical elements 124 each include alongitudinal axis. The longitudinal axis extends in a plane parallel tothe major surface 106, 108 of the light guide 102 for planar lightguides or along a surface contour for non-planar light guides 102. Withreference to FIG. 1, each football-shaped micro-optical element includesa longitudinal axis 132 extending parallel to the ridge 130. In otherembodiments where the micro-optical element is a shape other than thefootball shape, the longitudinal axis may be defined by one of thelength or width of the micro-optical element in a plane parallel to themajor surface 106, 108 of the light guide 102 for planar light guides oralong a surface contour for non-planar light guides 102. As an example,for a dragged truncated cone (not shown), the longitudinal axis mayextend along its length and intersect its oppositely rounded ends.

In some embodiments, the longitudinal axis extends along the longer ofthe length or width of the micro-optical element. In other embodiments,the longitudinal axis extends along the shorter of the length or widthof the micro-optical element. In some embodiments where the length andthe width of the micro-optical element are the same (e.g., amicro-optical element having a square base), the longitudinal axis mayextend along one of the length or the width of the micro-opticalelement. The longitudinal axis may be arranged closer to parallel to thelight input edge than an axis extending perpendicular to thelongitudinal axis and along the other of the length or width of themicro-optical element.

The longitudinal axis is distinguishable from other axes of themicro-optical element extending in a plane parallel to the major surface106, 108 of the light guide 102 for planar light guides or along asurface contour for non-planar light guides 102. Accordingly, somemicro-optical elements (e.g., a conical or frustoconical micro-opticalelement having a circular base) may not have a distinguishablelongitudinal axis.

In some embodiments, the micro-optical elements have the same ornominally the same shape, size, depth, height, slope angle, includedangle, and/or index of refraction. The term “nominally” encompassesvariations of one or more parameters that fall within acceptabletolerances in design and/or manufacture. As an example, each of themicro-optical elements 124 may have the same or nominally the samefootball shape shown in FIG. 1. In other embodiments, the micro-opticalelements may vary in one or more of shape, size, depth, height, slopeangle, included angle, and/or index of refraction. As an example, thelight guide 102 may include first micro-optical elements each having afootball shape with an included angle of 70 degrees, and secondmicro-optical elements each having a football shape with an includedangle of 120 degrees. This variation in micro-optical elements mayachieve a desired light output from the light guide over thecorresponding major surface(s). Accordingly, the reference numeral 124will be generally used to collectively refer to the differentembodiments of micro-optical elements.

Each micro-optical element 124 includes at least one surface configuredto refract or reflect light propagating in the light guide 102 andincident thereon such that the light is extracted from the light guide.Such surface(s) is also herein referred to as a light-redirectingsurface. With exemplary reference to the football-shaped micro-opticalelement 124 shown in FIG. 1, at least one of the first side surface 126and the second side surface 128 is a light-redirecting surface.

In some embodiments, the micro-optical elements 124 (e.g., the firstside surface 126 and the second side surface 128) have a low surfaceroughness. In this disclosure, the term “low surface roughness” refersto a defined surface roughness suitable for specularly reflecting orrefracting incident light. In one embodiment, the low surface roughnessis an average surface roughness (R_(a-low)) less than about 10.0 nm asmeasured in an area of 0.005 mm². In another embodiment, the low surfaceroughness is an average surface roughness (R_(a-low)) less than about5.0 nm as measured in an area of 0.005 mm². In another embodiment, thelow surface roughness is an average surface roughness (R_(a-low)) lessthan about 1.0 nm as measured in an area of 0.005 mm². A micro-opticalelement with all of its surfaces having a low surface roughness willalso be referred to as a low surface roughness micro-optical element. Asan example, in some embodiments, the low surface roughness micro-opticalelements may have an average surface roughness (R_(a-low)) ranging fromabout 0.5 nm to about 5.0 nm as measured in an area of 0.005 mm².

The micro-optical elements 124 may be arranged at the light guide 102 tospecularly extract light from the light guide 102 in a defined intensityprofile and with a defined light ray angle distribution. Accordingly,the micro-optical elements 124 may be arranged in an array correspondingto the light input edge 110. With additional reference to FIG. 2, eachof the micro-optical elements 124 are typically arranged in an array 125of linearly oriented micro-optical elements in order to achieve thisdesired light extraction. The term “array of linearly orientedmicro-optical elements” is defined as an array of micro-opticalelements, each micro-optical element having the same angular orientationrelative to one another. As exemplified in FIG. 2, the array 125 oflinearly oriented micro-optical elements includes an array offootball-shaped micro-optical elements, each football-shapedmicro-optical element arranged with its longitudinal axis 132 orientedin the same direction. That is, the longitudinal axes of themicro-optical elements 124 are parallel or nominally parallel to oneanother. In embodiments where the light input edge is a straight surface(e.g., as shown in FIGS. 1 and 2), the longitudinal axes of each of themicro-optical elements 124 may also be parallel to the light input edge.In embodiments where the light input edge is a curved surface, thelongitudinal axes of each of the micro-optical elements 124 may also beparallel to the tangent of at least a portion of the light input edge.

FIG. 3 is an output distribution profile showing far-field light rayangle distributions of light extracted from exemplary embodiment of thelight guide 102 shown in FIGS. 1 and 2 in which the micro-opticalelements 124 are arranged in an array of linearly oriented micro-opticalelements. Each of the micro-optical elements 124 are configured asfootball shaped micro-optical elements having an included angle of 120°.The degree scale shown in FIG. 3 represents an azimuth relative to thenormal of the major surface 106, 108. The output distribution profileshows the light distribution (vertical beam angle) in a first plane 1orthogonal to the light input edge 110 and to the major surfaces 106,108 of the light guide 102. For this distribution, the light source 104is arranged adjacent the light input edge 110 proximate 270°, the majorsurface 106 is arranged proximate 180°, and the major surface 108 isarranged proximate 0°. The output distribution profile also shows thelight distribution (horizontal beam angle) in a second plane 2orthogonal to the side edges 114, 116 and to the major surfaces 106, 108of the light guide 102. For this distribution, the major surface 106 isarranged proximate 180°, the major surface 108 is arranged proximate 0°,and the light source 104 is arranged normal to the plane of the page.

As shown in FIG. 3, for the first plane 1 (showing vertical beam angle),the micro-optical elements 124 arranged in the array of linearlyoriented micro-optical elements specularly reflect a first portion 150of the light input to the light guide 102 from the light source 104through the major surface 108 of the light guide 102 with a verticalbeam angle of about 30.0°. The first micro-optical elements 124 alsospecularly refract a second portion 152 of the light input to the lightguide 102 from the light source 104 through the major surface 106 of thelight guide 102 with a vertical beam angle of about 32.5°. For thesecond plane 2 (showing horizontal beam angle), the micro-opticalelements 124 arranged in the array of linearly oriented micro-opticalelements specularly reflect the first portion 150 of the light throughthe major surface 108 of the light guide 102 with a horizontal beamangle of about 100.0°. The first micro-optical elements 124 alsospecularly refract the second portion 152 of the light through the majorsurface 106 of the light guide 102 with a horizontal beam angle of about60.0°.

While the array 125 of linearly oriented micro-optical elements mayprovide specular light extraction from the light guide 102 in a definedintensity profile and with a defined light ray angle distribution, thislinear array also provides an optically-specular path extending into thelight guide 102 from the light input edge 110. As a result, the surfacesof the light guide 102 including the array 125 of linearly orientedmicro-optical elements create an imaging path back to the light source104, and reflections of the light source 104 as viewed through theoptically-specular path are visible to a viewer viewing the lightingassembly 100. The light source 104 includes discrete solid-state lightemitters 118 that create visual artifacts due to imaging of the lightsource 104. Accordingly, even if the micro-optical elements 124 arearranged to extract light in a uniform intensity profile over the majorsurface 106, 108, the optically-specular path creates the visual effectof one or more relatively high-intensity columns of light extendingalong the light guide 102 from the light input edge 110. This visualeffect is also referred to herein as a “headlighting” effect.

While the headlighting effect can be reduced by one or more opticaladjusters (not shown) (e.g., a diffusing film) located adjacent one orboth of the major surfaces 106, 108, the use of the optical adjustersfor such purpose destroys the directional, specular light outputdistribution of the light output from the lighting assembly 100. The useof the optical adjusters also lowers the efficiency of the lightingassembly 100. Furthermore, in many applications (e.g., as a lightingfixture, a sign, a display apparatus, etc.), the use of an opticaladjuster is not preferable (e.g., for aesthetic reasons).

In accordance with the present disclosure, and with exemplary referenceto FIGS. 1 and 4, micro-optical elements 124 are included in an array127 of rotated micro-optical elements corresponding to the light inputedge 110. The term “array of rotated micro-optical elements” is definedas an array of micro-optical elements, each micro-optical element havinga respective rotational orientation differing from among the rotationalorientations of other micro-optical elements in the array but by no morethan α°. In embodiments where the light input edge is a straight surface(e.g., as shown in FIGS. 1 and 4), the longitudinal axes of themicro-optical elements 124 is also arranged with its longitudinal axis132 within the range of ±θ° relative to the light input edge, with theangle of θ° being half of α°. In embodiments where the light input edgeis a curved surface (e.g., as shown in FIG. 13), the longitudinal axesof the micro-optical elements 124 may be arranged with its longitudinalaxis 132 within the range of ±θ° relative to the tangent of at least aportion of the light input edge, with the angle of θ° being half of α°.The angle θ is a positive or negative value to reference the directionof rotation of the micro-optical element. With reference to FIG. 4,rotation in a counter-clockwise direction may provide a positive value,and rotation in a clockwise direction may provide a negative value. Insome embodiments, this correlation of rotation direction topositive/negative angle may be reversed (e.g., counter-clockwise isconsidered negative and clockwise is considered positive).

In one example, each of the micro-optical elements 124 in the array 127of rotated micro-optical elements includes a longitudinal axis 132arranged within the range of +45° to −45° (±θ°) relative to the lightinput edge; and the respective rotational orientations from among therotational orientations of other micro-optical elements in the array 127differ by no more than 90°. In another example, each of themicro-optical elements 124 in the array 127 of rotated micro-opticalelements includes a longitudinal axis 132 arranged within the range of+30° to −30° (±θ°) relative to the light input edge; and the respectiverotational orientations from among the rotational orientations of othermicro-optical elements in the array 127 differ by no more than 60°. Inanother example, each of the micro-optical elements 124 in the array 127of rotated micro-optical elements includes a longitudinal axis 132arranged within the range of +15° to −15° (±θ°) relative to the lightinput edge; and the respective rotational orientations from among therotational orientations of other micro-optical elements in the array 127differ by no more than 30°. In another example, each of themicro-optical elements 124 in the array 127 of rotated micro-opticalelements includes a longitudinal axis 132 arranged within the range of+10° to −10° (±θ°) relative to the light input edge; and the respectiverotational orientations from among the rotational orientations of othermicro-optical elements in the array 127 differ by no more than 20°.

FIGS. 5 and 6 are SEM images specifically showing exemplarymicro-optical elements 124 configured as football-shaped micro-opticalelements. As shown, the micro-optical elements 124 included light guide102 are provided in an array of rotated micro-optical elements. In someembodiments, the micro-optical elements 124 in the array 127 of rotatedmicro-optical elements are the only micro-optical elements present atthe light guide.

At least a portion of the micro-optical elements 124 in the array 127have a longitudinal axis 132 that is non-parallel to the light inputedge 110. Accordingly, for a path linearly extending from the lightinput edge 110 along the light guide 102, at least one of themicro-optical elements along the path is arranged with the longitudinalaxis 132 thereof at a positive angle relative to the light input edge110 (or relative to the tangent of at least a part of the light inputedge, for a curved light input edge), and at least another one of themicro-optical elements 124 along the path is arranged with thelongitudinal axis 132 thereof at a negative angle relative to the lightinput edge (or relative to the tangent of at least a part of the lightinput edge, for a curved light input edge). FIG. 4 shows an exemplarypath extending along the light guide 102 orthogonal to the light inputedge 110 as the optical axis of a solid-state light emitter. Other pathsthat are non-orthogonal to the light input edge (e.g., non-parallel or“off-axis” to the optical axis 119 of a solid-state light emitter) mayalso intersect at least one of the micro-optical elements 124 arrangedwith the longitudinal axis 132 thereof at a positive angle relative tothe light input edge, and at least another one of the micro-opticalelements 124 arranged with the longitudinal axis 132 thereof at anegative angle relative to the light input edge.

The respective rotational orientations of the micro-optical elements 124in the array 127 of rotated micro-optical elements may be provided atrandom or in a predefined manner. In some embodiments, a portion of themicro-optical elements 124 in the array 127 of rotated micro-opticalelements are respectively arranged with the longitudinal axes 132thereof parallel or nominally parallel to the light input edge 110 (orthe tangent of at least a portion of the light input edge), and aportion of the micro-optical elements 124 in the array 127 of rotatedmicro-optical elements are respectively arranged with the longitudinalaxes 132 thereof non-parallel to the light input edge 110 (or thetangent of at least a portion of the light input edge). In someembodiments, the respective rotational orientations of the longitudinalaxes 132 of the micro-optical elements 124 in the array 127 may beuniformly distributed at the light guide 102. In an example, thepercentage of micro-optical elements having a given rotationalorientation from among the micro-optical elements at a given location atthe light guide 102 may be the same or nominally the same as thispercentage at any other location at the light guide 102. In anotherexample, the percentage of micro-optical elements having a givenrotational orientation from among the micro-optical elements at a givenlocation at the light guide 102 may be the same or nominally the same asthe percentage of micro-optical elements having a different rotationalorientation from among the micro-optical elements at the given location.In other embodiments, as described below, respective rotationalorientations of the micro-optical elements 124 in the array 127 ofrotated micro-optical elements may vary depending on their location atthe light guide 102.

The micro-optical elements 124 provided in the array 127 of rotatedmicro-optical elements are configured to reduce or eliminate theheadlighting effect by disrupting the optically-specular path extendingfrom the light input edge 110. The rotated micro-optical elements 124create images in varied directions based on their rotation, therebybreaking up an overall continuous image of the light input edge 110.This provides the visual effect of a nominally uniform light outputproximate the light input edge 110 to a viewer viewing the lightingassembly 100.

In addition to reducing headlighting, the array 127 of rotatedmicro-optical elements also provides similar ray angle control of thelight extracted from the light guide 102. FIGS. 7 and 8 are respectiveoutput distribution profiles showing far-field light ray angledistributions of light extracted from exemplary embodiments of the lightguide 102 shown in FIGS. 1 and 4. In the exemplary embodiment of thelight guide associated with FIG. 7, each of the micro-optical elements124 are configured as football shaped micro-optical elements having anincluded angle of 120° and having a longitudinal axis 132 arrangedwithin the range of +15° to −15° relative to the light input edge 110.In the exemplary embodiment of the light guide associated with FIG. 8,each of the micro-optical elements 124 are configured as football shapedmicro-optical elements having an included angle of 120° and having alongitudinal axis 132 arranged within the range of +30° to −30° relativeto the light input edge 110. Accordingly, the micro-optical elementsprovided in the exemplary light guides associated with FIGS. 7 and 8differ from the micro-optical elements provided in the exemplary lightguide associated with FIG. 2 in the rotation of the micro-opticalelements.

The output distribution profiles of each of FIGS. 7 and 8 show the lightdistributions (vertical beam angle and horizontal beam angle) inrespective first and second planes 1, 2 similar to those described abovewith respect to FIG. 3.

As shown in FIG. 7 (range of +15° to −15° relative to the light inputedge 110), for the first plane 1 (showing vertical beam angle), themicro-optical elements 124 specularly reflect a first portion 160 of thelight input to the light guide 102 from the light source 104 through themajor surface 108 of the light guide 102 with a vertical beam angle ofabout 30.0°. The micro-optical elements 124 also specularly refract asecond portion 162 of the light input to the light guide 102 from thelight source 104 through the major surface 106 of the light guide 102with a vertical beam angle of about 32.5°. For the second plane 2(showing horizontal beam angle), the micro-optical elements 124specularly reflect the first portion 160 of the light through the majorsurface 108 of the light guide 102 with a horizontal beam angle of about110.0°. The first micro-optical elements 124 also specularly refract thesecond portion 162 of the light through the major surface 106 of thelight guide 102 with a horizontal beam angle of about 60.0°.

As shown in FIG. 8 (range of +30° to −30° relative to the light inputedge 110), for the first plane 1 (showing vertical beam angle), themicro-optical elements 124 specularly reflect a first portion 170 of thelight input to the light guide 102 from the light source 104 through themajor surface 108 of the light guide 102 with a vertical beam angle ofabout 30.0°. The micro-optical elements 124 also specularly refract asecond portion 172 of the light input to the light guide 102 from thelight source 104 through the major surface 106 of the light guide 102with a vertical beam angle of about 35.0°. For the second plane 2(showing horizontal beam angle), the micro-optical elements 124specularly reflect the first portion 170 of the light through the majorsurface 108 of the light guide 102 with a horizontal beam angle of about110.0°. The first micro-optical elements 124 also specularly refract thesecond portion 172 of the light through the major surface 106 of thelight guide 102 with a horizontal beam angle of about 60.0°.

As shown from FIGS. 7 and 8, the specular light ray angle distributionsof light extracted from the light guide 102 are largely maintained inthe embodiments including the array 127 of rotated micro-opticalelements, as compared with the light ray angle distribution of lightextracted from the light guide 102 having the array 125 of linearlyoriented micro-optical elements. Specifically, the vertical beam angleassociated with the light guide including the array 127 of rotatedmicro-optical elements are largely the same as the vertical beam angleassociated with the light guide including the array 125 of linearlyoriented micro-optical elements. However, as the maximum rotationchanges from ±15° (FIG. 7) to ±30° (FIG. 8), the profile of the lightdoes slightly deviate from the profile of the array 125 of linearlyoriented micro-optical elements (FIG. 3.) It is also noted that thehorizontal beam angle does slightly widen to 110° in the examplesassociated with the light guide including the array 127 of rotatedmicro-optical elements as compared with the horizontal beam angle of100° associated with the light guide including the array 125 of linearlyoriented micro-optical elements.

In some embodiments, the array 127 of rotated micro-optical elements maybe configured so that the widening of the horizontal beam angle isintentionally imparted to the light extracted from the light guide. Thismay achieve a more uniform output distribution in the off-axis (e.g., anaxis parallel to the light input edge and perpendicular to the opticalaxis of the solid-state light emitter(s)). This intentional widening ofthe horizontal beam angle may be advantageous in embodiments where lightis input to the light guide at only one or less than all of the edgesurfaces.

The broader light ray angle distribution of the light extracted by thearray 127 of rotated micro-optical elements does slightly reduce thedirectional output of the light extracted from the light guide 102 as awhole. Accordingly, the micro-optical elements of the array 127 ofrotated micro-optical elements may be arranged to minimize thisreduction. Typically the headlighting effect manifests more strongly inclose proximity to the light input edge 110. Thus, the rotatedmicro-optical elements may be arranged in a particular manner to add toeffective reduction of the headlighting effect while maintaining anoverall directional light output of the lighting assembly 100.

In some embodiments, the percentage of rotated micro-optical elementsfrom among the micro-optical elements present at a given location of thelight guide decreases with increasing distance from the light inputedge. For example, with reference to FIG. 1, the percentage of rotatedmicro-optical elements from among the micro-optical elements present ata given location of the light guide may decrease with increasingdistance from the light input edge along the light guide from the lightinput edge 110 to the opposing edge surface 112. FIG. 1 shows threeexemplary locations 134, 136, 138 of the light guide 102. At a location134 proximate the light input edge 110, the percentage of micro-opticalelements having a longitudinal axis 132 arranged at an angle relative tothe light input edge 110 from among the micro-optical elements at thelocation 134 is highest, and the percentage of micro-optical elementshaving a longitudinal axis 132 parallel to the light input edge 110 islowest. In an example, the percentage of micro-optical elements having alongitudinal axis 132 arranged at an angle relative to the light inputedge 110 at the location 134 is about 75% to about 100%, and thepercentage of micro-optical elements having a longitudinal axis 132parallel to the light input edge 110 is about 0% to about 25%.

At a location 136 further from the light input edge 110, the percentageof micro-optical elements having a longitudinal axis 132 arranged at anangle relative to the light input edge 110 from among the micro-opticalelements at the location 136 is lower than the percentage at location134, and the percentage of micro-optical elements having a longitudinalaxis 132 parallel to the light input edge 110 is higher than thepercentage at location 134. In an example, the percentage ofmicro-optical elements having a longitudinal axis 132 arranged at anangle relative to the light input edge at the location 136 is about 25%to about 75%, and the percentage of micro-optical elements having alongitudinal axis 132 parallel to the light input edge 110 is about 25%to about 75%. At a location 138 still further from the light input edge110, the percentage of micro-optical elements having a longitudinal axis132 arranged at an angle relative to the light input edge 110 from amongthe micro-optical elements at the location 138 is lower than thepercentage at locations 134 and 136, and the percentage of micro-opticalelements having a longitudinal axis 132 parallel to the light input edge110 is higher than the percentage at locations 134 and 136. In anexample, the percentage of micro-optical elements having a longitudinalaxis 132 arranged at an angle relative to the light input edge at thelocation 138 is about 0% to about 25%, and the percentage ofmicro-optical elements having a longitudinal axis 132 parallel to thelight input edge is about 75% to about 100%.

In some embodiments, the maximum angle θ of the micro-optical elementshaving a longitudinal axis 132 arranged at an angle relative to thelight input edge 110 at a given location of the light guide 102decreases with increasing distance from the light input edge 110 alongthe light guide from the light input edge to the opposing edge surface.Accordingly, the angle α may also reduce as a function of distance fromthe light input edge. With continued reference to FIGS. 1 and 4, at alocation 134 proximate the light input edge 110, the maximum angle θ ofthe micro-optical elements 124 having a longitudinal axis 132 arrangedat an angle relative to the light input edge 110 is highest. In anexample, the maximum angle θ of the micro-optical elements 124 having alongitudinal axis 132 arranged at an angle relative to the light inputedge is ±30°. At a location 136 further from the light input edge 110,the maximum angle θ of the micro-optical elements having a longitudinalaxis 132 arranged at an angle relative to the light input edge 110 islower than the maximum angle θ at location 134. In an example, themaximum angle θ of the micro-optical elements 124 having a longitudinalaxis 132 arranged at an angle relative to the light input edge is ±15°.At a location 138 further from the light input edge 110, the maximumangle θ of the micro-optical elements 124 having a longitudinal axis 132arranged at an angle relative to the light input edge 110 is lower thanthe maximum angle θ at locations 134 and 136. In an example, the maximumangle θ of the micro-optical elements 124 having a longitudinal axis 132arranged at an angle relative to the light input edge is ±10°.

In some embodiments, at least a portion of the micro-optical elements124 in the array 127 of rotated micro-optical elements include at leastone surface having a high surface roughness. In this disclosure, theterm “high surface roughness” refers to a defined surface roughnesssuitable for imparting a diffuse component to incident light that isreflected or refracted. The high surface roughness is greater than thelow surface roughness described above. The high surface roughness is adefined roughness intentionally imparted to the at least one surface ofthe micro-optical element. In one embodiment, the high surface roughnessis an average surface roughness (R_(a-high)) equal or greater than about0.10 μm as measured in an area of 0.005 mm². In another embodiment, thehigh surface roughness is an average surface roughness (R_(a-high))ranging from about 0.10 μm to about 5.0 μm as measured in an area of0.005 mm². In another embodiment, the high surface roughness is anaverage surface roughness (R_(a-high)) ranging from about 0.30 μm toabout 3.0 μm as measured in an area of 0.005 mm². In another embodiment,the high surface roughness is an average surface roughness (R_(a-high))ranging from about 0.30 μm to about 1.0 μm as measured in an area of0.005 mm².

In this disclosure, the term “surface roughness” of a micro-opticalelement refers to the surface roughness of the roughest surface of themicro-optical element. For example a micro-optical element 124 isreferred to as having a high surface roughness (e.g., a high surfaceroughness micro-optical element) in embodiments where at least onesurface of the micro-optical element has a high surface roughness (e.g.,even if other surfaces of the micro-optical element have a low surfaceroughness).

The micro-optical elements 124 having the high surface roughness areadditionally configured to reduce or eliminate the headlighting effectby disrupting the optically-specular path extending from the light inputedge 110. The high surface roughness of the micro-optical element 124alters the optical characteristics of the side surface 126, 128 suchthat the side surface reflects and refracts light partially specularlyand partially diffusely.

FIG. 9 is an output distribution profile showing far-field light rayangle distributions of light extracted from an exemplary embodiment ofthe light guide 102 shown in FIGS. 1 and 4. In the exemplary embodimentof the light guide 102 associated with FIG. 9, each of the micro-opticalelements 124 are configured as football shaped micro-optical elementshaving an included angle of 115° and having a longitudinal axis arrangedwithin the range of +15° to −15° relative to the light input edge. Eachof the micro-optical elements 124 is also embodied as a high surfaceroughness micro-optical element having arcuate grooves formed on thesurfaces thereof. Accordingly, the micro-optical elements provided inthe exemplary light guide associated with FIG. 9 differ from themicro-optical elements provided in the exemplary light guide associatedwith FIG. 7 in the surface roughness of the micro-optical elements.

The output distribution profiles of FIG. 9 shows the light distributions(vertical beam angle and horizontal beam angle) in respective first andsecond planes 1,2 similar to those described above with respect to FIG.3

As shown in FIG. 9, for the first plane 1 (showing vertical beam angle),the micro-optical elements 124 specularly reflect a first portion of thelight input to the light guide 102 from the light source 104 through themajor surface 108 of the light guide 102 with a vertical beam angle ofabout 55.0°. The micro-optical elements 124 also specularly refract asecond portion 141 of the light input to the light guide 102 from thelight source 104 through the major surface 106 of the light guide 102with a vertical beam angle of about 47.5°. For the second plane 2(showing horizontal beam angle), the micro-optical elements 124specularly reflect the first portion of the light through the majorsurface 108 of the light guide 102 with a horizontal beam angle of about140.0°. The first micro-optical elements 124 also specularly refract thesecond portion 141 of the light through the major surface 106 of thelight guide 102 with a horizontal beam angle of about 70.0°.

By comparing FIGS. 7 and 9, it is apparent that the high surfaceroughness of the micro-optical elements 124 imparts a diffuse (e.g.,lambertian) component to the light extracted from the light guide 102.In other words, the high surface roughness of the second micro-opticalelements 124 provides a defined broadening of the peak of the light rayangle distribution of the light extracted from the light guide 102.

Because the array 127 of rotated micro-optical elements already providesat least some reduction of the headlighting, in some embodiments, thearray 127 of rotated micro-optical elements may include a portion ofmicro-optical elements 124 having a low surface roughness, and anotherportion of the micro-optical elements 124 having a high surfaceroughness. This embodiment of mixed low surface roughness and highsurface roughness micro-optical elements may provide a reduction ofheadlighting, while also improving the control over the light ray angledistribution as compared with an embodiment where each of themicro-optical elements in the array are high surface roughnessmicro-optical elements.

FIG. 10 is an output distribution profile showing far-field light rayangle distributions of light extracted from an exemplary embodiment ofthe light guide 102 shown in FIGS. 1 and 4. In the exemplary embodimentof the light guide associated with FIG. 10, a portion of themicro-optical elements 124 are configured as football shapedmicro-optical elements having an included angle of 115°, having alongitudinal axis 132 arranged within the range of +15° to −15° relativeto the light input edge 110, and having a high surface roughness fromarcuate grooves. Another portion of the micro-optical elements 124 areconfigured as football shaped micro-optical elements having an includedangle of 120°, having a longitudinal axis 132 arranged within the rangeof +15° to −15° relative to the light input edge 110, and having a lowsurface roughness. Accordingly, the micro-optical elements provided atthe exemplary light guide associated with FIG. 10 differ from themicro-optical elements provided in the exemplary light guide associatedwith FIG. 9 in that a portion of the micro-optical elements 124 are lowsurface roughness micro-optical elements.

The output distribution profiles of FIG. 10 shows the lightdistributions (vertical beam angle and horizontal beam angle) inrespective first and second planes 1, 2 similar to those described abovewith respect to FIG. 3.

As shown in FIG. 10, for the first plane 1 (showing vertical beamangle), the micro-optical elements 124 specularly reflect a firstportion of the light input to the light guide 102 from the light source104 through the major surface 108 of the light guide 102 with a verticalbeam angle of about 30.0°. The micro-optical elements 124 alsospecularly refract a second portion 141 of the light input to the lightguide 102 from the light source 104 through the major surface 106 of thelight guide 102 with a vertical beam angle of about 35.0°. For thesecond plane 2 (showing horizontal beam angle), the micro-opticalelements 124 specularly reflect the first portion of the light throughthe major surface 108 of the light guide 102 with a horizontal beamangle of about 95.0°. The first micro-optical elements 124 alsospecularly refract the second portion 141 of the light through the majorsurface 106 of the light guide 102 with a horizontal beam angle of about70.0°.

By comparing FIGS. 9 and 10, it is apparent that the mixed low surfaceroughness micro-optical elements and high surface roughnessmicro-optical elements provide an output distribution profile that ismore similar to the output distribution profiles shown in FIGS. 3, 7,and 8.

In some embodiments, the array 127 of rotated micro-optical elementsincludes a nominally uniform mix of low surface roughness micro-opticalelements and high surface roughness micro-optical elements. In anexample, the percentage of low surface roughness micro-optical elementsfrom among the micro-optical elements present at any given location ofthe light guide may be approximately 50%, and the percentage of highsurface roughness micro-optical elements from among the micro-opticalelements present at any given location of the light guide may beapproximately 50%. In another example, the percentage of low surfaceroughness micro-optical elements from among the micro-optical elementspresent at any given location of the light guide may be approximately75%, and the percentage of high surface roughness micro-optical elementsfrom among the micro-optical elements present at any given location ofthe light guide may be approximately 25%.

In other embodiments, the mix of low surface roughness micro-opticalelements and high surface roughness micro-optical elements in the array127 of rotated micro-optical elements varies as a function of locationon the light guide 102. Typically the headlighting effect manifests morestrongly in close proximity to the light input edge 110. Thus, the highsurface roughness micro-optical elements may be arranged in a particularmanner to add to effective reduction of the headlighting effect whilemaintaining an overall directional light output of the lighting assembly100.

In some embodiments, the percentage of high surface roughnessmicro-optical elements from among the micro-optical elements present ata given location of the light guide decreases with increasing distancefrom the light input edge along the light guide from the light inputedge to the opposing edge surface. With reference to FIG. 1, threeexemplary locations 134, 136, 138 of the light guide are identified. Ata location 134 proximate the light input edge 110, the percentage ofhigh surface roughness micro-optical elements from among themicro-optical elements at the location 134 is highest, and thepercentage of low surface roughness micro-optical elements is lowest. Inan example, the percentage of high surface roughness micro-opticalelements at the location 134 is about 50% to about 75%, and thepercentage of low surface roughness micro-optical elements is about 25%to about 50%. At a location 136 further from the light input edge 110,the percentage of high surface roughness micro-optical elements fromamong the micro-optical elements at the location 136 is lower than thepercentage at location 134, and the percentage of low surface roughnessmicro-optical elements is higher than at location 134. In an example,the percentage of high surface roughness micro-optical elements at thelocation 136 is about 25% to about 50%, and the percentage of lowsurface roughness micro-optical elements is about 50% to about 75%. At alocation 138 still further from the light input edge 110, the percentageof high surface roughness micro-optical elements from among themicro-optical elements at the location 136 is lower than the percentageat locations 134 and 136, and the percentage of low surface roughnessmicro-optical elements is higher than at locations 134 and 136. In anexample, the percentage of high surface roughness micro-optical elementsat the location 138 is about 0% to about 25%, and the percentage of lowsurface roughness micro-optical elements is about 75% to about 100%.

In some embodiments, the surface roughness of high surface roughnessmicro-optical elements decreases with increasing distance from the lightinput edge 110. The variation in surface roughness may be progressive orstep wise. Accordingly, the diffuse component imparted to the lightextracted from the light guide 102 by a high surface roughnessmicro-optical elements at a location proximate the light input edge 110(e.g., location 134) is greater than the diffuse component imparted tothe light extracted by a high surface roughness micro-optical elementdistal the light input edge 110 (e.g., location 136 or 138). In suchembodiments where the high surface roughness micro-optical elements 124mutually differ in surface roughness, this difference in the surfaceroughness among the high surface roughness micro-optical elements issubstantially less than the difference between the average surfaceroughness (R_(a-high)) of the high surface roughness surface(s) and theaverage surface roughness (R_(a-low)) of the low surface roughnessmicro-optical elements.

In the embodiments described above, the light guide 102 includes asingle light input edge 110, and the array 127 of rotated micro-opticalelements corresponds to the light input edge 110. In some embodiments,the light guide may include more than one light input edge. Although notspecifically shown in FIG. 1, one or more of the edge surface 112, 114,116 may be an additional light input edge, and an additional lightsource may be positioned adjacent the additional light input edge. Also,in some embodiments, the light guide may include an additional array ofrotated micro-optical elements corresponding to the additional lightinput edge.

With reference to FIGS. 1 and 4, in one example, the edge surface 114may be an additional light input edge. In the example, the light inputedge 110 is considered a first light input edge; the array 127 ofrotated micro-optical elements corresponding to the light input edge 110is considered a first array of rotated micro-optical elements; and thelight source 104 is considered a first light source. The edge surface114 is considered a second light input edge. The light guide may includea second array of rotated micro-optical elements corresponding to thesecond light input edge 114. The second array of rotated micro-opticalelements may at least partially overlap the first array of rotatedmicro-optical elements.

In another example, the edge surface 112 may be an additional lightinput edge. In the example, the light input edge 110 is considered afirst light input edge, and the light source 104 is considered a firstlight source. The edge surface 112 is considered a second light inputedge. Because the second light input edge 112 is opposite the firstlight input edge 110, the array of rotated micro-optical elementscorresponding to the first light input edge 110 may also correspond tothe second light input edge 112. Accordingly, in some embodiments, asingle array of rotated micro-optical elements may correspond to morethan one (e.g., two) light input edge.

FIG. 11 shows an exemplary lighting assembly 200 including a light guidehaving more than one light input edge. The light guide of FIG. 11 mayinclude similar features to the light guide described above with respectto FIG. 1. The light guide 102 is circular in shape and includes planarmajor surfaces 106, 108. The light guide 102 includes edge surfacesextending between the major surfaces 106, 108, the edge surfacesincluding a first light input edge 210, second light input edge 212, andthird light input edge 214. The light input edges are spaced equallyapart from one another around the perimeter such that each light inputedge is arranged approximately 120° on the perimeter from another one ofthe light input edges. A light source 104 a, 104 b, 104 c isrespectively located adjacent to each light input edge. Each lightsource 104 a, 104 b, 104 c may include similar features to the lightsource described above with respect to FIG. 1.

In the illustrated example, the light guide includes three arrays 127 a,127 b, 127 c of rotated micro-optical elements, each array correspondingto one of the respective light input edges 210, 212, 214. For example, afirst array 127 a of rotated micro-optical elements includesmicro-optical elements arranged with their respective longitudinal axes132 within the range of ±θ° relative to the first light input edge 210.Micro-optical elements shown in FIG. 11 that are included in the firstarray are identified as micro-optical elements 124 a. A second array 127b of rotated micro-optical elements includes micro-optical elementsarranged with their respective longitudinal axes 132 within the range of±θ° relative to the second light input edge 212. Micro-optical elementsshown in FIG. 11 that are included in the second array 127 b areidentified as micro-optical elements 124 b. A third array 127 c ofrotated micro-optical elements includes micro-optical elements arrangedwith their respective longitudinal axes 132 within the range of ±θ°relative to the third light input edge 214. Micro-optical elements shownin FIG. 11 that are included in the third array 127 c are identified asmicro-optical elements 124 c. Embodiments of the first array 127 a ofrotated micro-optical elements, the second array 127 b of rotatedmicro-optical elements, and the third array 127 c of rotatedmicro-optical elements are similar to the embodiments of the array 127of rotated micro-optical elements discussed above with respect to FIGS.1 and 4.

For each array 127 a, 127 b, 127 c of rotated micro-optical elements, atleast a portion of the micro-optical elements have a longitudinal axisthat is non-parallel to the corresponding light input edge. Accordingly,for a path 240 extending from the first light input edge 210 along thelight guide, at least one of the micro-optical elements 124 a along thepath is arranged with the longitudinal axis 132 thereof at a positiveangle relative to the light input edge 210, and at least another one ofthe micro-optical elements 124 a along the path is arranged with thelongitudinal axis 132 thereof at a negative angle relative to the lightinput edge 210. For a path 242 extending from the second light inputedge 212 along the light guide, at least one of the micro-opticalelements 124 b along the path is arranged with the longitudinal axis 132thereof at a positive angle relative to the light input edge 212, and atleast another one of the micro-optical elements 124 b along the path isarranged with the longitudinal axis 132 thereof at a negative anglerelative to the light input edge 212. For a path 244 extending from thethird light input edge 214 along the light guide, at least one of themicro-optical elements 124 c along the path is arranged with thelongitudinal axis 132 thereof at a positive angle relative to the lightinput edge 214, and at least another one of the micro-optical elements124 c along the path is arranged with the longitudinal axis 132 thereofat a negative angle relative to the light input edge 214.

In some embodiments, the arrays 127 a, 127 b, 127 c at least partiallyoverlap. As an example, FIG. 11 shows that a location 220 proximate thecenter of the light guide 102 may include micro-optical elements fromeach of the arrays 127 a, 127 b, 127 c. Other locations of the lightguide may include micro-optical elements from only one of the arrays 127a, 127 b, 127 c. For example, at location 222 proximate the first lightinput edge 210, the light guide may only include micro-optical elements124 a from the first array 127 a of rotated micro-optical elements. Atlocation 224 proximate the second light input edge 212, the light guidemay only include micro-optical elements 124 b from the second array 127b of rotated micro-optical elements. At location 222 proximate the thirdlight input edge 214, the light guide may only include micro-opticalelements from the third array 127 c of rotated micro-optical elements.In other embodiments, the arrays 127 a, 127 b, 127 c may completelyoverlap so that micro-optical elements 124 a, 124 b, 124 c of each ofthe arrays 127 a, 127 b, 127 c are present at each of locations 222,224, and 226.

FIG. 12 shows another exemplary lighting assembly 300 including a lightguide having more than one light input edge. The light guide 102 issimilar to the light guide described in FIG. 11, but includes four lightinput edges 310, 312, 314, 316. The light input edges 310, 312, 314, 316are spaced equally apart from one another around the perimeter such thateach light input edge is arranged approximately 90° on the perimeterfrom another one of the light input edge. A light source 104 d, 104 e,104 f, 104 g is respectively located adjacent to each light input edge.Each light source 104 d, 104 e, 104 f, 104 g may include similarfeatures to the light source described above with respect to FIG. 1.

In the illustrated example, the light guide includes two arrays 127 d,127 e of rotated micro-optical elements, each array corresponding to twoof the respective light input edges. For example, a first array 127 d ofrotated micro-optical elements includes micro-optical elements arrangedwith their respective longitudinal axes 132 within the range of ±θ°relative to the first light input edge 310. The third light input edge314 is opposite the first light input edge 310, and the first array 127d also corresponds to the third light input edge 314 such thatmicro-optical elements are arranged with their respective longitudinalaxes 132 within the range of ±θ° relative to the third light input edge314. Micro-optical elements shown in FIG. 12 that are included in thefirst array 127 d are identified as micro-optical elements 124 d. Asecond array 127 e of rotated micro-optical elements includesmicro-optical elements arranged with their respective longitudinal axes132 within the range of ±θ° relative to the second light input edge 312.The fourth light input edge 316 is opposite the first light input edge312, and the second array 127 e also corresponds to the fourth lightinput edge 314 such that micro-optical elements are arranged with theirrespective longitudinal axes 132 within the range of ±θ° relative to thefourth light input edge 316. Micro-optical elements shown in FIG. 11that are included in the second array 127 e are identified asmicro-optical elements 124 e. Embodiments of the first array 127 d ofrotated micro-optical elements and the second array 127 e of rotatedmicro-optical elements are similar to the embodiments of the array ofrotated micro-optical elements discussed above with respect to FIGS. 1and 4.

For each array 127 d, 127 e of rotated micro-optical elements, at leasta portion of the micro-optical elements included therein have alongitudinal axis that is non-parallel to the corresponding light inputedge. Accordingly, for a path 340 extending from the first light inputedge 310 along the light guide, at least one of the micro-opticalelements 124 d along the path is arranged with the longitudinal axis 132thereof at a positive angle relative to the light input edge 310, and atleast another one of the micro-optical elements 124 d along the path isarranged with the longitudinal axis 132 thereof at a negative anglerelative to the light input edge 310. Similarly, for a path 344extending from the third light input edge 314 along the light guide, atleast one of the micro-optical elements 124 d along the path is arrangedwith the longitudinal axis 132 thereof at a positive angle relative tothe light input edge 310, and at least another one of the micro-opticalelements 124 d along the path is arranged with the longitudinal axis 132thereof at a negative angle relative to the light input edge 310. For apath 342 extending from the second light input edge 312 along the lightguide, at least one of the micro-optical elements 124 e along the pathis arranged with the longitudinal axis 132 thereof at a positive anglerelative to the second light input edge 312, and at least another one ofthe micro-optical elements 124 e along the path is arranged with thelongitudinal axis 132 thereof at a negative angle relative to the secondlight input edge 312. Similarly, for a path 346 extending from thefourth light input edge 314 along the light guide, at least one of themicro-optical elements 124 e along the path is arranged with thelongitudinal axis 132 thereof at a positive angle relative to the fourthlight input edge 314, and at least another one of the micro-opticalelements 124 e along the path is arranged with the longitudinal axis 132thereof at a negative angle relative to the fourth light input edge 314.

In some embodiments, the arrays 127 d, 127 e at least partially overlap.As an example, FIG. 12 shows that a location 320 proximate the center ofthe light guide 102 may include micro-optical elements from each of thefirst and second arrays 127 d, 127 e. Other locations of the light guidemay include micro-optical elements from only one of the arrays. Forexample, at location 322 proximate the first light input edge 310 (andat location 326 proximate the third light input edge 314), the lightguide may only include micro-optical elements 124 d from the first array127 d of rotated micro-optical elements. At location 324 proximate thesecond light input edge 312 (and at location 328 proximate the fourthlight input edge 316), the light guide may only include micro-opticalelements 124 e from the second array 127 e of rotated micro-opticalelements. In other embodiments, the arrays 127 d, 127 e may completelyoverlap so that micro-optical elements 124 e and 124 e of each of thearrays 127 d, 127 e are present at each of locations 322, 324, 326, and328.

FIG. 13 shows another exemplary lighting assembly 400 including a lightguide 102 having more than one light input edge. The light guide 102 issimilar to the light guide described in FIG. 12, but includes curvedlight input edges 410, 412, 414, 416. The light input edges 410, 412,414, 416 are spaced equally apart from one another around the perimetersuch that each light input edge is arranged approximately 90° on theperimeter from another one of the light input edges. A light source 104h, 104 i, 104 j, 104 k is respectively located adjacent to each lightinput edge. Each light source 104 h, 104 i, 104 j, 104 k may includesimilar features to the light source described above with respect toFIG. 1.

In the illustrated example, the light guide includes two arrays 127 d,127 e of rotated micro-optical elements, each array corresponding to twoof the respective light input edges. For example, a first array 127 d ofrotated micro-optical elements includes micro-optical elements arrangedwith their respective longitudinal axes 132 within the range of ±θ°relative to a tangent of a part (e.g., a midpoint) of the first lightinput edge 410. The third light input edge 414 is opposite the firstlight input edge 410, and the first array 127 d also corresponds to thethird light input edge 414 such that micro-optical elements are arrangedwith their respective longitudinal axes 132 within the range of ±θ°relative to a tangent of a part (e.g., a midpoint) of the third lightinput edge 414. Micro-optical elements shown in FIG. 13 that areincluded in the first array 127 d are identified as micro-opticalelements 124 d. A second array 127 e of rotated micro-optical elementsincludes micro-optical elements arranged with their respectivelongitudinal axes 132 within the range of ±θ° relative to a tangent of apart (e.g., a midpoint) of the second light input edge 412. The fourthlight input edge 416 is opposite the first light input edge 412, and thesecond array 127 e also corresponds to the fourth light input edge 414such that micro-optical elements are arranged with their respectivelongitudinal axes 132 within the range of ±θ° relative to a tangent of apart (e.g., a midpoint) of the fourth light input edge 416.Micro-optical elements shown in FIG. 13 that are included in the secondarray 127 e are identified as micro-optical elements 124 e. Embodimentsof the first array 127 d of rotated micro-optical elements and thesecond array 127 e of rotated micro-optical elements are similar to theembodiments of the array of rotated micro-optical elements discussedabove with respect to FIGS. 1 and 4.

For each array 127 d, 127 e of rotated micro-optical elements, at leasta portion of the micro-optical elements included therein have alongitudinal axis that is non-parallel to the tangent of a part of thecorresponding light input edge. Accordingly, for a path 440 extendingfrom the first light input edge 410 along the light guide, at least oneof the micro-optical elements 124 d along the path is arranged with thelongitudinal axis 132 thereof at a positive angle relative to thetangent 411 of a part of the light input edge 410, and at least anotherone of the micro-optical elements 124 d along the path is arranged withthe longitudinal axis 132 thereof at a negative angle relative to thetangent 411 of a part of the light input edge 410. Similarly, for a path444 extending from the third light input edge 414 along the light guide,at least one of the micro-optical elements 124 d along the path isarranged with the longitudinal axis 132 thereof at a positive anglerelative to the tangent 415 of a part of the light input edge 414, andat least another one of the micro-optical elements 124 d along the pathis arranged with the longitudinal axis 132 thereof at a negative anglerelative to the tangent 415 of a part of the light input edge 414. For apath 442 extending from the second light input edge 412 along the lightguide, at least one of the micro-optical elements 124 e along the pathis arranged with the longitudinal axis 132 thereof at a positive anglerelative to the tangent 413 of a part of the second light input edge412, and at least another one of the micro-optical elements 124 b alongthe path is arranged with the longitudinal axis 132 thereof at anegative angle relative to the tangent 413 of a part of the second lightinput edge 412. Similarly, for a path 446 extending from the fourthlight input edge 416 along the light guide, at least one of themicro-optical elements 124 e along the path is arranged with thelongitudinal axis 132 thereof at a positive angle relative to thetangent 417 of a part of the fourth light input edge 416, and at leastanother one of the micro-optical elements 124 e along the path isarranged with the longitudinal axis 132 thereof at a negative anglerelative to the tangent 417 of a part of the fourth light input edge416.

In some embodiments, the arrays 127 d, 127 e at least partially overlap.As an example, FIG. 13 shows that a location 420 proximate the center ofthe light guide 102 may include micro-optical elements from each of thefirst and second arrays. Other locations of the light guide may includemicro-optical elements from only one of the arrays 127 d, 127 e. Forexample, at location 422 proximate the first light input edge 410 (andat location 426 proximate the third light input edge 414), the lightguide may only include micro-optical elements 124 d from the first array127 d of rotated micro-optical elements. At location 424 proximate thesecond light input edge 412 (and at location 428 proximate the fourthlight input edge 416), the light guide may only include micro-opticalelements 124 e from the second array 127 e of rotated micro-opticalelements. In other embodiments, the arrays 127 d, 127 e may completelyoverlap so that micro-optical elements 124 d and 124 e of each of thearrays are present at each of locations 422, 424, 426, and 428.

In the embodiments described above including more than one light inputedge (FIGS. 11-13), the lighting assembly 200, 300, 400 may beconfigured such that the light output from the light guide issymmetrical. More specifically, the multiple light input edges in theseembodiments of the lighting assembly 200, 300, 400 are arranged aroundthe circumference of the light guide and relative to respective arraysof micro-optical elements such that the light may be output from thelight guide in a symmetric manner in a plane parallel to the majorsurfaces of the light guide. FIG. 14 shows an exemplary embodiment of alighting assembly 500 including a light guide having more than one lightinput edge in which the light guide is configured to output lighttherefrom in an asymmetric manner in a plane parallel to the majorsurfaces of the light guide.

The light guide 102 of FIG. 14 may include similar features to the lightguide described above with respect to FIG. 1. The light guide 102 hasthe shape of an octagon and includes planar major surfaces 106, 108. Thelight guide 102 includes edge surfaces extending between the majorsurfaces 106, 108, the edge surfaces including a first light input edge510 and a second light input edge 512. The light input edges 510, 512are separated by edge surface 514 and are arranged such that a normal oflight input edge 510 is arranged approximately 90° relative to a normalof the light input edge 512. A light source 104 m, 104 n is respectivelylocated adjacent to each light input edge 510, 512. Each light source104 m, 104 n may include similar features to the light source describedabove with respect to FIG. 1.

In the illustrated example, the light guide includes two arrays 127 m,127 n of rotated micro-optical elements, each array corresponding to oneof the respective light input edges 510, 512. For example, a first array127 m of rotated micro-optical elements includes micro-optical elementsarranged with their respective longitudinal axes 132 within the range of±θ° relative to the first light input edge 510. Micro-optical elementsshown in FIG. 14 that are included in the first array are identified asmicro-optical elements 124 m. A second array 127 n of rotatedmicro-optical elements includes micro-optical elements arranged withtheir respective longitudinal axes 132 within the range of ±θ° relativeto the second light input edge 512. Micro-optical elements shown in FIG.14 that are included in the second array 127 n are identified asmicro-optical elements 124 n. Embodiments of the first array 127 m ofrotated micro-optical elements and the second array 127 n of rotatedmicro-optical elements are similar to the embodiments of the array 127of rotated micro-optical elements discussed above with respect to FIGS.1 and 4.

For each array 127 m, 127 n of rotated micro-optical elements, at leasta portion of the micro-optical elements have a longitudinal axis that isnon-parallel to the corresponding light input edge. Accordingly, for apath 540 extending from the first light input edge 510 along the lightguide, at least one of the micro-optical elements 124 m along the pathis arranged with the longitudinal axis 132 thereof at a positive anglerelative to the light input edge 510, and at least another one of themicro-optical elements 124 m along the path is arranged with thelongitudinal axis 132 thereof at a negative angle relative to the lightinput edge 510. For a path 542 extending from the second light inputedge 512 along the light guide, at least one of the micro-opticalelements 124 n along the path is arranged with the longitudinal axis 132thereof at a positive angle relative to the light input edge 512, and atleast another one of the micro-optical elements 124 n along the path isarranged with the longitudinal axis 132 thereof at a negative anglerelative to the light input edge 512.

At location 520 proximate the first light input edge 510, the lightguide may only include micro-optical elements 124 m from the first array127 m of rotated micro-optical elements. At location 522 proximate thesecond light input edge 512, the light guide may only includemicro-optical elements 124 n from the second array 127 n of rotatedmicro-optical elements.

In some embodiments, the arrays 127 m, 127 n at least partially overlap.As an example, FIG. 14 shows that a location 524 distal the light inputedges 510, 512 may include micro-optical elements from each of thearrays 127 m, 127 n. In other embodiments (not shown), a location 524distal the light input edges 510, 512 may include a third array. In suchembodiments, the arrays 127 m, 127 n may not be present at the locationof the third array. In some examples, the third array may be an array oflinearly oriented micro-optical elements, each micro-optical elementhaving its longitudinal axis parallel to the edge surface 514. In otherexamples, the third array may be an array of rotated micro-opticalelements, each micro-optical element arranged with its longitudinal axis132 within the range of ±θ° relative to the light input edge.

In some embodiments, the arrays 127 m and 127 n may be configured toinfluence the asymmetric output distribution of light from the lightguide. As an example, for the lighting assembly 500 of FIG. 14, agreater percentage of optical elements in the array 127 m may be rotatedto have its longitudinal axis 132 closer to parallel to the edge surface514 than the percentage of optical elements in the array 127 m rotatedto have its longitudinal axis 132 further from parallel to the edgesurface 514. Similarly, a greater percentage of optical elements in thearray 127 n may be rotated to have its longitudinal axis 132 closer toparallel to the edge surface 514 than the percentage of optical elementsin the array 127 n rotated to have its longitudinal axis 132 furtherfrom parallel to the edge surface 514. Such configuration may influencethe asymmetric output distribution of light from the light guide.

In this disclosure, the phrase “one of” followed by a list is intendedto mean the elements of the list in the alterative. For example, “one ofA, B and C” means A or B or C. The phrase “at least one of” followed bya list is intended to mean one or more of the elements of the list inthe alterative. For example, “at least one of A, B and C” means A or Bor C or (A and B) or (A and C) or (B and C) or (A and B and C).

What is claimed is:
 1. A lighting assembly, comprising: a light guide to propagate light by total internal reflection, the light guide comprising opposed major surfaces and a light input edge extending between the major surfaces in a thickness direction through which light is input into the light guide, wherein: the major surfaces of the light guide are configured in the shape of an octagon, the light guide including edge surfaces extending between the major surfaces defined by the respective sides of the octagon shape; and the light input edge is located at one of the edge surfaces of the light guide; a light source located adjacent the light input edge to edge light the light guide; and an array of micro-optical elements of well-defined shape at at least one of the opposed major surfaces, the array of micro-optical elements corresponding to the light source, each of the micro-optical elements in the array comprising a longitudinal axis arranged within the range of +45° to −45° relative to the light input edge, wherein a path linearly extending along the light guide from the light input edge intersects at least a portion of the micro-optical elements in the array, at least one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a positive angle relative to the light input edge, and at least another one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a negative angle relative to the light input edge.
 2. The lighting assembly of claim 1, wherein the longitudinal axis of each of the micro-optical elements in the array is arranged within the range of +30° to −30° relative to the light input edge.
 3. The lighting assembly of claim 1, wherein the longitudinal axis of each of the micro-optical elements in the array is arranged within the range of +15° to −15° relative to the light input edge.
 4. The lighting assembly of claim 1, wherein a portion of the micro-optical elements are respectively arranged with the longitudinal axis thereof nominally parallel to the light input edge.
 5. The lighting assembly of claim 1, wherein the micro-optical elements of the array have nominally the same shape.
 6. The lighting assembly of claim 1, wherein at least a portion of the micro-optical elements each comprise a first surface intersecting the major surface and a second surface intersecting the major surface, the second surface additionally intersecting the first surface to form an arcuate ridge extending along the longitudinal axis of the micro-optical element and that additionally intersects the major surface at both of its ends, the arcuate ridge extending parallel to the longitudinal axis of the micro-optical element.
 7. The lighting assembly of claim 1, wherein: a portion of the micro-optical elements of the array comprise micro-optical elements having a low surface roughness; another portion of the micro-optical elements comprise micro-optical elements having a high surface roughness greater than the low surface roughness; and a percentage of the micro-optical elements that are the micro-optical elements having a high surface roughness decreases with increasing distance from the light input edge.
 8. The lighting assembly of claim 1, wherein the light guide further comprises an additional light input edge extending between the major surfaces in a thickness direction through which light is input into the light guide; the lighting assembly further comprises an additional light source located adjacent the additional light input edge to edge light the light guide; and the light guide further comprises an additional array of micro-optical elements of well-defined shape at at least one of the opposed major surfaces, the additional array of micro-optical elements corresponding to the additional light source, each of the micro-optical elements in the additional array comprising a longitudinal axis arranged within the range of +45° to −45° relative to the additional light input edge, wherein a path linearly extending along the light guide from the additional light input edge intersects at least a portion of the micro-optical elements of the additional array, at least one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a positive angle relative to the additional light input edge, and at least another one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a negative angle relative to the additional light input edge.
 9. The lighting assembly of claim 8, wherein the array of micro-optical elements and the additional array of micro-optical elements are configured to asymmetrically output light from the light guide in a plane parallel to the opposed major surfaces.
 10. The lighting assembly of claim 8, wherein: the additional light input edge is located at another one of the edge surfaces of the light guide.
 11. A light guide, comprising: opposed major surfaces between which light propagates by total internal reflection; a light input edge extending between the major surfaces in a thickness direction through which light is input into the light guide, wherein: the major surfaces of the light guide are configured in the shape of an octagon, the light guide including edge surfaces extending between the major surfaces defined by the respective sides of the octagon shape; and the light input edge is located at one of the edge surfaces of the light guide; and an array of micro-optical elements of well-defined shape at at least one of the opposed major surfaces, the array of micro-optical elements corresponding to the light input edge, each of the micro-optical elements in the array comprising a longitudinal axis arranged within the range of +45° to −45° relative to the light input edge, wherein a path linearly extending along the light guide from the light input edge intersects at least a portion of the micro-optical elements in the array, at least one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a positive angle relative to the light input edge, and at least another one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a negative angle relative to the light input edge.
 12. The light guide of claim 11, wherein the longitudinal axis of each of the micro-optical elements in the array is arranged within the range of +30° to −30° relative to the light input edge.
 13. The light guide of claim 11, wherein the longitudinal axis of each of the micro-optical elements in the array is arranged within the range of +15° to −15° relative to the light input edge.
 14. The light guide of claim 11, wherein a portion of the micro-optical elements are respectively arranged with the longitudinal axis thereof nominally parallel to the light input edge.
 15. The light guide of claim 11, wherein at least a portion of the micro-optical elements each comprise a first surface intersecting the major surface and a second surface intersecting the major surface, the second surface additionally intersecting the first surface to form an arcuate ridge extending along the longitudinal axis of the micro-optical element and that additionally intersects the major surface at both of its ends.
 16. The light guide of claim 11, wherein the light guide further comprises an additional light input edge extending between the major surfaces in a thickness direction through which light is input into the light guide; and an additional array of micro-optical elements of well-defined shape at at least one of the opposed major surfaces, the additional array of micro-optical elements corresponding to the additional light source, each of the micro-optical elements in the additional array comprising a longitudinal axis arranged within the range of +45° to −45° relative to the additional light input edge, wherein a path linearly extending along the light guide from the additional light input edge intersects at least a portion of the micro-optical elements of the additional array, at least one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a positive angle relative to the additional light input edge, and at least another one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a negative angle relative to the additional light input edge.
 17. The light guide of claim 16, wherein the array of micro-optical elements and the additional array of micro-optical elements are configured to asymmetrically output light from the light guide in a plane parallel to the opposed major surfaces.
 18. The light guide of claim 16, wherein the additional light input edge is located at another one of the edge surfaces of the light guide.
 19. A light guide, comprising: opposed major surfaces between which light propagates by total internal reflection; a light input edge extending between the major surfaces in a thickness direction through which light is input into the light guide; and an array of micro-optical elements of well-defined shape at at least one of the opposed major surfaces, the array of micro-optical elements corresponding to the light input edge, each of the micro-optical elements in the array comprising a longitudinal axis arranged within the range of +45° to −45° relative to the light input edge, wherein a path linearly extending along the light guide from the light input edge intersects at least a portion of the micro-optical elements in the array, at least one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a positive angle relative to the light input edge, and at least another one of the micro-optical elements along the path arranged with the longitudinal axis thereof at a negative angle relative to the light input edge; and wherein: a portion of the micro-optical elements of the array comprise micro-optical elements having a low surface roughness; another portion of the micro-optical elements comprise micro-optical elements having a high surface roughness greater than the low surface roughness; and a percentage of the micro-optical elements that are the micro-optical elements having a high surface roughness decreases with increasing distance from the light input edge.
 20. A lighting assembly, comprising: the light guide of claim 19; and a light source located adjacent the light input edge to edge light the light guide. 